The invention covers a nuclear power plant with a closed system of circulating cooling gas. The equipment consists of a high-temperature reactor, a gas turbine assembly and heat exchangers. The latter are made up of recuperators, pre- and intermediate coolers as well as pipes carrying the gas between the several components. The entire assembly is encased in a housing made of pre-stressed concrete (single-unit construction).
Plants of the type described offer obvious advantages over nuclear power installations of a different, existing type in which the energy is transferred to a secondary circuit, because they combine the advantages of gas turbines with the high efficiency and simplicity in operation which is typical of single-circuit construction. By integrating the reactor, the turbines, the required coolers, and all other circuit components in a single pressure tight vessel, separate connecting elements connecting the components that contain "live" fuel are rendered unnecessary, a fact which offers distinct advantages in the construction and operation of high-temperature reactors. The integrated design is therefore preferred for a large number of specialized nuclear power plants.
For example, German Auslegeschrift No. 1,156,903 describes a compact power plant of the above-mentioned type intended for vehicles. In this design the turbine and the compressor are located on opposite faces of the reactor core, a hollow shaft passing through the core, with intermediate coolers being located in the annular space between the reactor and the wall of the pressure chamber.
In this compact design it is assumed that the turbine used will not require any maintenance, and therefore no provision has been made for the removal of the turbine or any other components of the circuit.
A similar construction is shown in a nuclear reactor disclosed in German Offenlegungschrift No. 2,005,208 where a pressure jacket, open at its frontal surfaces, is located inside the pressure chamber and is spaced relative to the inside wall of the pressure vessel so as to accommodate the heat exchangers.
Also, the German Offenlegungsschrift No. 2,028,736 a nuclear power plant is described having a system of closed circulation of gas. This power plant is built on the principle of dual chambers. The gas turbine together with the components belonging to the gas circulation system are contained in a block of prestressed concrete separate from the concrete pressure vessel, with the object of simplifying the fueling- and controlling processes.
A similar construction is used in the high-pressure concrete vessel described in German Auslegeschrift No. 1,614,610, consisting of two separate pressure-tight chambers, one containing the reactor, the other the secondary equipment. The working medium is carried by pipes protruding through the pressure-tight walls, first from the reactor to the turbine and from the compressor then back into an annular-shaped space below the reactor core. This so-called "igloo-method" however offers technical difficulties in construction, and the nuclear power plant, because of the principles applied in the arrangement of components, is highly uneconomical.
German Offenlegungsschrift No. 2,062,934 likewise discloses a gas-cooled nuclear reactor of integrated construction in which the gas turbine is located inside the hollow wall of the pressure chamber enclosing the reactor core. Through a by-pass mechanism a part of the cooling gas carried past the core of the reactor can be diverted and directly combined with the hot exhaust gas emitted from the core.
Another nuclear power plant of the type originally defined is described in German Offenlegungsschrift No. 1,764,249. Here the nuclear reactor together and all circulatory components are located in closely spaced, parallel, vertical shafts inside the concrete pressure vessel, with all components being fully accessible from the outside. Passages for the cooling media are provided within the wall of the pressure vessel as well as between the several vertical shafts. In this design the cooling media has to flow over an extensive area, resulting in the need for a relatively bulky pressure vessel in this type plant.